Two Caribbean fruits, Blighia sapida Konig (ackee) and Muntingia calabura L. (Jamaica cherry), are being examined for plant-derived antioxidants that may be useful in the prevention of coronary heart disease. In preliminary studies, the capsules of the ackee fruit and Jamaica cherry fruit were extracted with methanol and partitioned sequentially with hexane and ethyl acetate (EtOAc). EtOAc extracts revealed high antioxidant activity for ackee (IC50 = 30.4 mug/ml) and Jamaica cherry (IC50 = 5.0 mug/ml) in the 1,1-diphenyl-2-picrylhydrazy1 (DPPH) free radical assay. This activity is comparable to vitamins C and E. Preliminary isolation work on ackee suggests a flavonoid may be one of the antioxidant constituents. A phenolic antioxidant, methyl gallate, and a saponin were isolated from the EtOAc extract of ackee by open column chromatography. Further isolation of antioxidant from the remaining extracts of ackee, and Jamaica cherry will be performed by activity-guided fractionation using various chromatographic techniques. The structures of all purified active constituents will be determined through standard spectrometric techniques including mass spectrometry and nuclear magnetic resonance. Purified antioxidant constituents from ackee and Jamaica cherry will be tested in an in vitro LDL oxidation assay to determine their protective effects against LDL oxidation.